Treatment of leather



Patented July 23, 1940 UNlTED STATES TREATMENT 028' LEATHER Joseph W. Johnson and John J. Brophy, Salem,

and Alexis E. Ushakoif, Beverly, Mass, assignors to United Shoe Machinery Corporation, Borough of Flemington, N. J., a corporation of New Jersey No Drawing. Ap lication November 15, 1937,

Serial No. 174,652

8 Claims.

given a predetermined shape during the period of temporary inertness.

Other objects are to provide a method of and composition for rendering leather temporarily inert in a very short period of time and maintaining sa'id leather in inert condition for a controlled length of time. A further object is to leave the leather in softened condition after the period of temporary inertness is over.

In accordance with the above and other objects the present invention contemplates subjecting leather simultaneously to the action of a penetrant and an inerting agent. Where it is desired to impart a permanent softening effect to the leather, the leather may be simultaneously treated with a softening agent. The leather treatment, according to the present invention, preferably is accomplished by preparing a composition containing the desired ingredients and then immersing the leather in such composition for a relatively short time, usually not exceeding a few minutes.

The penetrant constituent of the inerting composition consists of one or more liquids capable of wetting the substance of the leather and of penetrating rapidly thereinto. Such constituent may be said to possess positive capillarity for the leather. The penetrant may consist of one or more organic compounds of a group to be described in detail hereinafter and of which group illustrative examples are toluene, amyl chloride and methyl acetate.

The inerting agent of the leather treating composition is capable of exerting an inerting effect on leather in the ordinary air-dry condition. The group from which the inerting agent may be selected is given in detail hereinafter. Illustrative examples are acetone, ethyl alcohol and ethylene glycol monoethyl ether.

The softening agent, an optional constituent of the leather treating composition and which may be employed when it is desired to impart a permanent softened condition to the leather, may be selected from a group of high boiling point liquids. Illustrative examples are dibutyl phthalate, castor oil, and hexahydrophenol.

The present invention finds advantageous application in the shoe industry. Thus, leather outsoles treated in accordance with this'invention,

may be brought rapidly into inert condition and by suitable selection of the ingredients of the treating composition with respect to volatility the S-dichloroethylene outsole may be caused to remain in inert condition for apredetermined length of time, during which period shoemaking operations involving shaping of the leather, such as sole-laying and sole-attaching, may be accomplished. Moreover, the leather is not plumped or swelled as a result of the inerting operation whereby resultant disadvantages, such as distortion, are eliminated. .A further factor of importance is that the drying of the leather following the inerting operation may be of controlled duration, and is independent of the percentage. of moisture in the atmosphere. The outsoles thus may be subjected to further shoe factory operations such as bufling and finishing within a relatively short time. Moreover, since uniform drying conditions may be maintained throughout the year, regardless of the degree of humidity of the air, the shoe factory schedule is not affected by variations in atmospheric humidity. Further advantages resulting from theuse of this invention are that, even when no softening agent is employed, there is no stiffening effect on the leather following the inerting operation and, furthermore, the gloss and grain finish of leather outsoles are not deleteriously af-' fected. Furthermore. no constituents of the leather are removed as a result of its association with the inerting composition and no leaching action on the leather takes place.

The penetrant constituent of the leather inerting composition may consist of one or more of a large number of organic liquids which are capable of rapidly penetrating and wetting the substance of leather, and thereby accelerating the effective ness of the inerting agent. The organic substances which have been successfully employed for this purpose include the following:

Gasoline (High testn-Amyl chloride saturated aliphatic Mixed amyl chlorides Propylene dichloride Ethylene dichloride Methyl acetate It will be noted that the above group includes representatives of the organic classes known as aliphatic hydrocarbons, cyclic hydrocarbons, chlorinated hydrocarbons, ketones, ethers and esters.

The inerting constituent of the leather treating composition may include one or more compounds of a group including various ketones, alcohols, esters and cyclic ethers of the glycols. It may be noted that some compounds such as methyl acetate appear to function both as penetrants and as inerting agents. Substances which have given Methyl acetate highly satisfactory results as inerting agents include the following aliphatic compounds:

Propylene oxide Diacetone alcohol Ethyl acetate Methyl alcohol Ethylene glycol mono- Ethyl alcohol ethyl ether Of the above group acetone has been found particularly efiicacious for the purpose.

When it is desired not only to produce a temporary inerting effect on the leather but also to accomplish a permanent softening thereof, one or more softening agents may be incorporated in the leather inerting composition. Materials which have been found suitable for this purpose include the following:

Acetone Methyl ethyl ketone Dibutyl phthalate Castor oil Dimethyl phthalate Sperm oil Diamyl phthalate Sulphonated castor oil Diethyl phthalate Hexahydrophenol The specific examples enumerated are essentially esters and organic oils of high boiling point.

The invention preferably is carried out by mixing the desired penetrant and inerting constituents and immersing the leather in the resulting composition. When permanent softness is to be imparted to the leather, softening material is incorporated in the inerting composition. The penetrant and inerting compounds may be selected and blended with a view to their volatility in order that the leather to be treated may remain in inert condition for a predetermined length of time. The greater the volatility of the ingredients of the inerting composition the shorter will be the period during which the leather, after treatment, will remain in inert condition.

Generally speaking, leather which is in airdry condition, that is to say, containing some moisture, may be more readily rendered inert than leather which is in bone dry or anhydrous condition.

The following specific examples illustrate the range of variation in the inerting composition and the variation in time during which the leather may be caused to remain in inert condition. In each case a leather outsole in air-dry condition was immersed in the liquid inerting composition and removed after a period of immersion noted below. It will be noted that the compositions are non-aqueous, and that the inerting agents, penetrants, and softening agents are organic liquids. It will further be noted that the leather treated by the following compositions becomes inert relatively quickly and that the leather remains in inert condition for periods varying with the volatility of the composition.

Example I Parts by volume Diacetone alcohol 8 Ethyl acetate 33 Ethyl alcohol 30 Hexahydrophenol 24 Tetrahydronaphthalene 24 Methyl acetate 24 A piece of outsole leather was immersed in the above composition for a period of 30 seconds. At the time of removal from the composition the leather was in inert condition and had absorbed inerting composition to the extent of 25% of the weight of the leather.

Example II Parts by volume Methyl acetate 48 Diacetone alcohol 36 Hexahydrophenol 8 Mesityl oxide 4 Gasoline 41 A leather outsole immersed for 45 seconds was in inert condition when removed from the composition, at which time it had absorbed the inerting composition to the extent of 25% of its weight. The leather remained in inert condition for 3 hours, and after 6 hours was in airdry condition.

Example III Parts by volume Methyl acetate 55 Diacetone alcohol 23 Hexahydfirophenol ua 2 Acetone 12 Ethylene dichloride 8 A piece of outsole leather absorbed 25% of its weight in 30 seconds, at which time upon removal from the composition it was found to be in inert condition. The leather remained in inert condition for 2 hours and after 4 hours was dry.

Example IV Parts by volume Methyl acetate 40 Acetone 10 Diacetone alcohol 25 Dibutyl phthalate 25 A piece of outsole leather was immersed in the composition for 30 seconds. In this period the leather had absorbed the composition to the extent of 25% of its weight and was in inert condition. The leather remained in temper for 8 hours and was dry in 12 hours. After the leather had become dry it was 46% more flexible than untreated leather, as determined by a deflection test of pieces of leather supported at one end and weighted at the other, and 120% more flexible than similar leather which had been tempered by means of water and subsequently permitted to dry.

Example V Parts by volume Methyl acetate Acetone 10 Dibutyl phthalat 5 Toluene 10 A leather outsole was immersed in the composition for 15 seconds. At this time the leather was in inert condition and had absorbed the composition to the extent of 25% of the weight of the leather. The leather remained in inert condition for about 45 minutes and after 1 hour was dry.

Example VI Parts by volume Methyl acetate 135 Acetone 135 Diacetone alcohol 10 Castor oil 20 Outsole leather which had been in dry storage for about two years was immersed in the composition for 1 /2 minutes, at which time the leather was in inert condition. The leather had 20% by weight of the leather. Three hours after the immersion, the grain surface of the leather was satisfactorily buifed.

Example VII Parts by volume Gasoline 40 Acetone g 40 Ethylene glycol monoethyl ether 15 Dibutyl phthalate A very hard and firm piece of outsole leather which could not satisfactorily be tempered in water was successfully rendered inert by immersion in the above composition.

Example VIII 1 Parts by volume Propylene dichloride Ethyl acetate 10 Methyl acetate 25 Acetone 25 Ethylene glycol monoethyl ether Dibutyl phthalate 10 A very hard and firm piece of outsole leather which could not satisfactorily be tempered in water was successfully rendered inert by immersion in the above composition.

Having described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. The method of rendering leather temporarily inert which comprises subjecting said leather simultaneously to the action of methyl acetate and an inerting agent.

2. The method of rendering leather temporarily inert which comprises subjecting said leather simultaneously to the action of non-aqueous, organic materials including acetone as an agent for rendering said leather temporarily inert, and a penetrant for accelerating the eifectiveness of the acetone.

3. The method of rendering leather temporarily inert 'which comprises treating said'leather simultaneously to the action of methyl acetate, acetone and dibutyl phthalate.

4. A composition for rendering leather temporarily inert which comprises methyl acetate and an inerting agent.

5. A non-aqueous composition for rendering leather temporarily inert which comprises an organic penetrant and acetone.

6. The method of rendering leather temporarily inert which comprisesimmersing said leather in a non-aqueous, liquid organic composition containing an agent for rendering said leather temporarily inert from the group of aliphatic compounds consisting of ketones, alcohols, esters,

7. A non-aqueous, organic composition for rendering leather temporarily inert which comprises an inerting agent from the group of aliphatic compounds consisting of ketones, alcohols, esters, and cyclic ethers of the glycols, and a penetrant for accelerating the efiectiveness of said inerting agent. I

8. A non-aqueous, organic composition for treating leather which comprises an inerting agent from the group of aliphatic compounds consisting of ketones, alcohols, esters, and cyclic ethers of the glycols, a penetrant for accelerating the effectiveness of said inerting agent, and a softener.

JOSEPH W. JOHNSON. JOHN J. BROPI-IY. ALEXIS E. USHAKOFF. 

